1. Field of the Invention
The present invention relates to mechanical presses and more particularly to adjustment of the press drive and corresponding alteration of the slide displacement vs. gear angle curve without disassembly.
2. Description of the Related Art
Mechanical presses of the type performing stamping and drawing operations employ a conventional construction that includes a frame structure having a crown and a bed portion and which supports a slide in a manner enabling reciprocating movement toward and away from the bed. A press drive assembly including a main gear and a crankshaft is arranged to convert rotary-oscillatory motion into the rectilinear reciprocating motion of the slide. These press machines are widely used for a variety of workpiece operations employing a large selection of die sets, with the press machine varying considerably in size and available tonnage depending on its intended use.
Mechanical presses, such as stamping presses and drawing presses, are provided a main gear which imparts rotational motion to a crankshaft. The crankshaft has an eccentric portion, or an eccentric crank link which translates the rotational motion of the crankshaft into reciprocal mechanical activity that is transmitted to the slide through a connecting arm. One complete rotation of the crankshaft produces one complete reciprocating motion of the slide.
Depending upon the type of drive mechanism utilized, the crankshaft can maintain a constant rotational velocity or an irregular rotational velocity. Irregular rotational velocity of the crankshaft is advantageous in press applications wherein reduction of the slide velocity near the bottom of the stroke (i.e. bottom dead center) is required so that the draw speed of the material is not exceeded. Additionally, slide velocity reduction near the bottom of the stroke reduces die wear, press vibration and noise. Presses which utilize different arrangements to produce irregular rotational velocity of the crankshaft are known in the art.
A standard press arrangement which produces constant rotational velocity of the crankshaft consists of a crankshaft and main gear arrangement wherein the crankshaft and main gear are concentric. Irregular rotational velocity of the crankshaft of a mechanical press can be achieved by differing arrangements of the crankshaft and the main gear wherein the crankshaft and the main gear are eccentric and are connected by a link drive assembly. Arrangements such as a link drive create an irregular rotational velocity which is beneficial in that they can be utilized to reduce the velocity of the slide near bottom dead center so that the draw speed of a particular material is not exceeded. Such arrangements are additionally beneficial in that they reduce die wear, press vibration and noise.
Presses utilizing similarly sized main gears may be more suitable for a particular workpiece depending upon whether a link drive or a slider crank drive arrangement is used. The ability to alter the drive mechanism of a mechanical press from a slider crank drive to differing link drive arrangements is advantageous in that one particular press may be utilized for different operations. The desire to create a flexible use mechanical press has led to modular type units being utilized. These modular unit presses allow for differing drive mechanisms to be inserted so that the press will operate as a pure slider crank drive or alternatively as a link type drive. Different modular units may be used to create different link drive arrangements and geometries. That is to say, link drive arrangements in which the distance between the center line of the crankshaft and the center line of the main gear is different as well as utilizing links of variable length. The distance between the center line of the main gear and the center line of the crankshaft as well as link lengths will be varied depending upon the modular unit chosen, but will be variable only at steps defined by the particular modular units manufactured and utilized.
The ability to vary the drive of a press in this way makes the press more versatile in its application, however, having to stop the press for a long period of time to make this adjustment is problematic. Press down time is experienced while drive mechanisms are exchanged. Room to store a number of modular units must also be provided. Additionally, the space in which the press resides must provide enough room above the crown so that different drive mechanisms may be removed and inserted. Currently, the purchaser of a press must utilize the drive mechanism with which the press is initially equipped or must utilize a press which offers different modular drive units and experience the problems mentioned above.
The present invention is directed to improve upon the aforementioned mechanical press drive adjustment mechanisms wherein it is desired to adjust the drive mechanism of a mechanical press without experiencing down time and without requiring an inventory of mechanism parts.
The present invention provides an adjustable drive mechanism for a mechanical press which includes the ability to change the position of the drive gear relative to the crankshaft without disassembly of the press.
The invention, in one form thereof, comprises an adjustable drive mechanism for a press. This adjustable drive mechanism includes a link drive and a crankshaft connected to the link drive. Adjustment means are utilized to change the position of the link drive relative to the crankshaft so that the slide velocity vs. distance off bottom dead center curve of the press is altered. The adjustment means changes the position of the link drive without press disassembly.
The invention, in another form thereof, comprises an adjustable drive mechanism for a press which includes a link drive, a crankshaft and a drive pinion. The drive pinion has a center line which defines the axis of rotation of the drive pinion. Adjustment means changes the position of the link drive without disassembly of the drive mechanism. Changing the position of the link drive alters the slide velocity vs. distance off bottom dead center curve of the press. In this form of the current invention, the adjustment means rotates the link drive about the center line of the drive pinion.
In one form of the current invention, the link drive includes a main gear having a center line, a gear link, a crank link and a crankshaft. A first end of the gear link is pivotally connected at one end of an eccentric portion of the main gear. The second end of the gear link is pivotally connected to a first end of the crank link. The second end of the crank link is pivotally connected to the crankshaft.
The invention, in another form thereof, comprises an adjustable drive mechanism for a press. In this form, the adjustable drive mechanism includes a link drive, a crankshaft, a drive pinion and adjustment means. The drive pinion has a center line which defines its axis of rotation. The adjustment means look rotates the link drive about the center line of the drive pinion. The adjustment means can be, for example, a partial gear and rotation means for rotating the partial gear about the drive pinion center line. The partial gear has the same axis of rotation as the drive pinion and rotatably supports the main gear. The rotation means can be, for example, a partial gear drive pinion, a hydraulic adjustment means, or a screw adjustment means. If a partial gear drive pinion is utilized as the rotation means, the partial gear drive pinion will selectively rotate the partial gear about the drive pinion center line. Hydraulic adjustment means and/or screw adjustment means (if employed) will have a first end operably connected to the press and a second end operably affixed to an eccentric portion of the partial gear so that actuation of the hydraulic adjustment means and/or screw adjustment means will cause the partial gear to rotate about the drive pinion center line.
Attachment means may be employed for affixing the partial gear to the press when the press is operating. The attachment means can be, for example, an axially moveable clamp.
The invention, in another form thereof, comprises an adjustable drive mechanism for a press which includes a link drive, a crankshaft, a drive pinion and adjustment means. The adjustment means is utilized to change the position of the link drive which consequently alters the slide velocity vs. distance off bottom dead center curve of the press. The adjustment means can be utilized to change the position of the link drive without disassembly of the drive mechanism. A drive pinion is utilized to drive the link drive. The drive pinion has a center line which defines the axis of rotation of the drive pinion. The adjustment means rotates the link drive about the center line of the drive pinion. The link drive includes a main gear which has a center line, a gear link and a crank link. The gear link has a first end which is pivotally connected to an eccentric portion of the main gear. The second end of the gear link is pivotally connected to a first end of the crank link. The second end of the crank link is connected to the crankshaft. In one form of the current invention, the center line of the drive pinion and the center line of the main gear form a substantially horizontal line when the main gear is concentric with the crankshaft.
The invention, in another form thereof, comprises a method of altering the drive mechanism of a mechanical press. In this form, this method comprises the steps of: providing a drive mechanism which includes a drive pinion, a main gear driven by the drive pinion and a crankshaft which is driven by the main gear; and changing the position of the main gear relative to the drive pinion. In one form of the current invention, the step of changing the position of the main gear relative to the drive pinion comprises rotating the main gear about the drive pinion.
The invention, in another form thereof, comprises a method which includes the step of rotating the main gear about the drive pinion. In this form of the current invention, the step of rotating the main gear about the drive pinion comprises the steps of: providing a partial gear, using the partial gear to rotatably support the main gear, and rotating the partial gear about the drive pinion.
The invention, in another form thereof, comprises a method of altering the drive mechanism of a mechanical press which includes the step of rotating the main gear about the drive pinion. In one form of the current invention, the step of rotating the main gear about the drive pinion comprises the steps of: providing a partial gear, using the partial gear to rotatably support the main gear, and rotating the partial gear about the drive pinion. In one form of the current invention, the step of rotating the partial gear about the drive pinion comprises the steps of: providing a partial gear drive pinion, engaging the partial gear drive pinion in driving relationship with the partial gear, and actuating the partial gear drive pinion.
The invention, in another form thereof, comprises a method of altering the drive mechanism of a mechanical press which includes the step of rotating the main gear about the drive pinion. In one form of the current invention, the step of rotating the main gear about the drive pinion comprises the steps of: providing a partial gear, using the partial gear to rotatably support the main gear, and rotating the partial gear about the drive pinion. In one form of the current invention, the step of rotating the partial gear about the drive pinion comprises the steps of: providing a hydraulic adjustment means, connecting the hydraulic adjustment means to the press, connecting the hydraulic adjustment means to the partial gear, and actuating the hydraulic adjustment means to rotate the partial gear.
The invention, in another form thereof, comprises a method of altering the drive mechanism of a mechanical press which includes the step of rotating the main gear about the drive pinion. In one form of the current invention, the step of rotating the main gear about the drive pinion comprises the steps of: providing a partial gear, using the partial gear to rotatably support the main gear, and rotating the partial gear about the drive pinion. In one form of the current invention, the step of rotating the partial gear about the drive pinion comprises the steps of: providing a screw adjustment means, connecting the screw adjustment means to the press, connecting the screw adjustment means to the partial gear, and actuating the screw adjustment means to rotate the partial gear.
The invention, in another form thereof, comprises a press. The press includes a crown and a driveshaft which is rotatably supported by the crown. A drive pinion is mechanically coupled to the driveshaft. The drive pinion has a center line which defines its axis of rotation. A main gear is driven by the drive pinion. A partial gear rotatably supports the main gear. The partial gear is utilized to rotate the main gear about the center line of the drive pinion. When the partial gear is not being utilized to rotate the main gear, it is fixedly supported by the crown and rotatably supports the main gear during press operation. The partial gear is arranged to be rotatably supported by the crown when it is utilized to rotate the main gear. When not rotating the main gear, the partial gear is fixedly supported by the crown. Rotating the main gear alters the slide velocity vs. distance off bottom dead center curve of the press. Attachment means are utilized for affixing the partial gear to the press when the press is operating. The attachment means can be, for example, an axially movable clamp. A partial gear drive pinion selectively rotates the partial gear about the drive pinion center line. In this way, the partial gear drive pinion actuates the partial gear so that the partial gear will rotate the main gear. The main gear is connected through a link arrangement to the crankshaft so that rotation of the main gear alters the drive mechanism of the mechanical press from a slider crank to varying link drive arrangements.
An advantage of the present invention is the ability to create a versatile use press that has a drive mechanism which can be altered from a pure slider crank to a link drive mechanism without disassembly such that press down time is effectively minimized or eliminated.
Another advantage of the present invention is that flexibility of use for a mechanical press can be achieved without having to purchase and store a large number of different modular drive units.
Another advantage of the present invention is that the drive mechanism of the mechanical press is adjustable from a slider crank configuration to multiple link drive configurations.
A further advantage of the present invention is that increased ceiling height is not required above the flexible drive press.